Napoleon Hair (watch beginning)
Neutron activation analysis (old)- 18 min
Napoleon Poisoning Claims Debunked
Hair EvidenceClass evidence
1st job: determine if animal or human
Composed of protein (keratin), an appendage of the skin that grows out of hair follicle
Each species possesses hair w/ characteristics length, color, shape, root appearance & internal features
Types of hair recovered & condition & number of hairs collected all impact their value as evidence
Function of Hair
Regulate body temp
Decrease friction
Protect against sunlight
Sense organ
Camoflauge
Phases (development stages)Anagen
Cyclical growth
Initial growth period where follicle is actively producing hair (materials are deposited in cells)
May last 3-6 years, 80-90 % of hair is this phase
Follicular tag- root is attached to follicle for growth, when hair is yanked out root is still attached- can use tag for DNA
Catagen
Transition period
Occurs between anagen & telogen phases
2% in this phase
Roots are elongated
Telogen
Resting phase
10-18% of hair
Most commonly found piece of evidence
Last about 100 days, easily dislodged
Root is club shaped
Final growth phase in which hair sheds
Parts of Hair
Hair is an appendage of the skin that grows out of an organ known as the hair follicle
Hair follicle: origin of growth of the root, shaft and tip club shaped structure in skin w/ network of
blood vessels called papilla that supply nutrients
Shaft: composed of protein keratin, consists of 3 layers
Cuticle
Allows hair to be resistant to chemicals & allows hair to retain structural features over a long timeFormed by overlapping scale (hardened cells)Scales on animals look like roof shinglesScales can be: coronal, spinous, or imbricateStudy by making casts (embedded in nail polish)
Cortex
Main body of hair
Contained w/ in the protective cuticle
Made of spindle-shaped cortical cells aligned in the shaft
Pigment granules found in cortex (major use in evidence- get diff. shapes, color, distribution)
Can look at cortex if you prepare slide w/ liquid that has same index of refrac. as hair
Medulla
Collection of cells having the appearance of a central canal running through hair
Varies among individuals
Classified as continuous, interrupted, fragment, absent
Medullary index (M.I.) = diameter of medulladiameter of shaft
Pubic
Need 25 hairs, routinely compared (head hair- normally 50)
Not subject to change (sample can be taken 1 year after crime- can still be compared)
Course and wiry, buckling can be present
Facial
Not meaningful, establish contact
Coarse, triangular cross section
Wide medulla, razor cut tip
Animal Hair
Used to link a suspect or location
Get transfer (from animal or secondary source)
Animals don’t possess enough indvl. microscopic characteristics to be associated w/ 1 particular animal
Can determine type of animal or breed
Animal hairs vary- in color & length from different parts of the body
Collect full length hairs
Some hairs found may be cut fur coat, rug, etc
Animals vs. Humans
Animal
MI ½ or greater
Medulla= continuous or interupted
Shape = patterned Cat=pearl Deer = spheres
Human
MI 1/3 or less
Medulla= fragmented or absent
Shape = cylindrical
Age and Sex
Age Can’t be determined definitively by microscope But hairs in infants finer, less distinctive Older hair finer, more variable in diameter
Sex Can do DNA w/ follicular tag (rare) Can also stain the sex chromatin in cells (Barr
body or y-body) Treated (perm,color) more frequent in females
Racial Determination
Caucasoid (European) Fine to medium coarseness Straight or wavy Blonde to brown/black in color Shafts – round to oval in cross section Have medium sized, evenly distributed pigment
granules Color- blonde, red, brown or black
Mongoloid (Asian) Coarse, straight, circular cross section Wider diameter Cuticle thicker Medulla continuous & wide Pigment granules are larger than caucasoid,
densely distributed Can have reddish appearance
Negroid (African) Curly, kinky Flattened cross section Pigment granules are larger than other groups-
in clumps Can be buckled (twisted shaft) & shaft is
frequently split
Identification and comparison of hair
Hair is class evidence
Identification involves: Scale structure, medullary index, medullary
shape
Compare: Color, length, diameter, medullary charac.,
cortical cells, artificial pigmentation (dyed or pigmentation – 1cm/month growth)
Analysis Techniques
Microscopy: Compound Comparison (most common) Fluorescence Electron
Neutron Activation Analysis- method of analysis that determines the composition of elements
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